
for line in open("Shendure_cSNPs.txt"):
    cols = line.strip().split("\t")
    if cols[0]=="Chromosome":
        continue
    loc = "chr%s:%s" % (cols[0], cols[1])
    oldBase = cols[2]
    observed = {}
    for obs in cols[3:]:
        for bb in obs.split("/"):
            if bb!="N":
                observed[bb] = True
    for obs in observed.keys():
        if obs != oldBase:
            print "%s\t%s\t%s" % (loc, oldBase, obs)

